In case a vehicle develops an abnormal symptom while the vehicle is driving, it is customary to energize a waning lamp on the instrument panel of the vehicle to give a warning or the like to the driver. On account of the abnormal symptom or the warning, the user takes the vehicle to the dealer or a repair shop where the vehicle is diagnosed or repaired.
The operator (technician) who is responsible for repairing the vehicle connects a fault diagnosing apparatus to an electronic control unit (hereinafter referred to as “ECU”) on the faulty vehicle, and reads out information such as a trouble code or the like of the fault that was stored in the ECU at the time of occurrence of the fault, thereby identifying a faulty system, i.e., an electric circuit undergoing the fault, with relative ease. Fault diagnosing apparatus of the type described above are widely used in the art. One such fault diagnosing apparatus is disclosed in U.S. Pat. No. 5,491,631 (hereinafter referred to as “U.S. Pat. No. 5,491,631 A”), for example.
There is a situation where though the user of a vehicle has complained about an abnormal symptom several times, there is no trouble code recorded, and the technician in charge fails to recreate the symptom despite attempts made to recreate the symptom in view of the complaint and hence finds it difficult to repair the vehicle.
To deal with a repair difficulty, a large-capacity storage device as disclosed in Japanese Laid-Open Patent Publication No. 2008-070133 (hereinafter referred to as “JP 2008-070133 A”) is temporarily connected to the ECU of a vehicle in question, and the user of the vehicle is asked to drive the vehicle for several days. While the vehicle is driven, data required for a fault diagnosis (driving parameter data) are collected in the storage device. The collected data are analyzed using a fault diagnosing machine or a fault analyzing apparatus to make a detailed diagnosis of the vehicle.
Driving parameter data are collected by a sequence of periodic exchanges of requests sent to a system control ECU for internal information and data sent from the system control ECU in response to the requests. If the fault diagnosing machine is to communicate with one or more certain ECUs through an intravehicular network, e.g., a CAN, to which a plurality of ECUs are connected, then the communications pose a new burden on the intravehicular network and tend to increase the bus usage rate.
Depending on the way in which the vehicle is driven, the bus usage rate may become temporarily so high that it may not be possible to obtain driving parameter data due to network congestion.
In case driving parameter data cannot be obtained, a vehicle data collecting apparatus disclosed in JP 2008-070133 A sends a request for resending data as indicated in FIGS. 13, 14 and paragraphs [0050] through [0053] of JP 2008-070133 A. In other words, the disclosed vehicle data collecting apparatus attempts to collect as much data as possible continuously even if responses are delayed or are not produced. If data come in an increased number of types or in an increased size, then those data which are less important are allowed to drop out for strictly synchronous periodic data retrieval.